The invention relates to a device in accordance with the preamble of claim 1, as well as to a method for producing ice cream by means of this device. The known machinery for producing ice cream is employed in connection with commercial ice cream production, for example in ice cream parlors.
The basic principle is the same with all machines: the liquid mixture in the processing container is partially and repeatedly applied to the cooled wall of the processing container by means of a processing tool, is cooled there, frozen, and scraped off again and returned to the not yet frozen liquid mixture; once the entire amount of the liquid mixture has frozen into an ice cream mass of the desired consistency and quality, it is taken from the processing container.
A differentiation is made in connection with the known discontinuously operating machines between those which are equipped with a rotating vertical vat with cooled wall surfaces, from which the finished ice cream must be removed by means of a large spatula, and those which have a horizontally placed vat and expel the finished ice cream by means of a processing tool.
DE-U-84 38 146.9 discloses a representative of the first mentioned type with the typical disadvantages: filling and emptying take place from the top of the processing container, which is slightly inclined in respect to the vertical direction, a trained specialist is required for removing the finished ice cream with the spatula, since it is dangerous to remove ice cream from the rotating vat. Characteristic for vertically operating machine are the continuous monitoring of the production process by freezing and extended production times; processing the ice cream and cleaning the vat with hands and lower arms in the very cold moist area leads to known health risks; the advantage of this classic machine type rests in a well-kneaded structure and a very low temperature of the finished ice cream.
Therefore there has been no lack of attempts to achieve a similarly good ice cream quality by means of different structural principles:
DE-OS 33 07 016 discloses a device in accordance with the species, wherein the processing container is horizontally arranged, with this device the longitudinal axis of the cylindrical container I extends horizontally. The manipulating end of the device is closed off by a cover, in which a filling funnel for introducing the liquid mixture and a removal opening for removing the finished ice cream are located. The tools for processing the liquid mixture are embodied in several parts: a rotating element is used for coating the wall of the processing container with the liquid mixture, an also rotating kneading and ejecting element, which additionally moves axially back and forth in the longitudinal axis of the processing container, is used for kneading the ice cream mass being formed by means of scraping elements, for the permanent scraping off of the liquid mixture applied to the inner wall, and finally for ejecting the finished ice cream through the removal opening.
With this machine with the horizontal processing container, processing of the liquid mixture is performed at a low number of revolutions, for ejecting the finished ice cream the number of revolutions is increased in order to speed up this process and to prevent thawing effects. However, ice cream of unsatisfactory quality is produced with this device since, because of the narrow diameter of the processing container and the comparatively quite high rotational speed it has little time to freeze on the wall of the processing container, with this machine it must not freeze too solidly in order to still convey the ice cream out from the rear to the front through the removal opening of the processing vat at a high number of revolutions by means of the ejection element.
Because of the high ejection speed and the narrow cross section of the removal opening, frictional heat is conveyed to the frozen mass of ice cream, which heats the ice cream mass and begins to degrade the structure and the texture of the ice cream; emptying of the processing container is only incomplete. Finally the structure of the device in accordance with the species is very expensive in comparison with the not completely satisfactory results.
EP 0 495 211 A1, which defines the species, discloses a multi-purpose device which can also be used for the discontinuous preparation of ice cream, wherein the processing container is horizontally arranged. At the manipulation end, the device is closed by means of a cover in which a filling funnel for introducing the liquid mixture and a closeable removal opening for taking out the finished ice cream are located. The tools for processing the liquid mixture consist of an agitator with three spatulas. Because of their construction with many components, the known ice cream machines require a large cleaning outlay, since many joints, open edges and seals (for example a fixedly attached run-off plate) exist, which come into direct contact with the ice cream. They therefore constitute a good culture medium for dangerous bacteria, for example salmonella. For this reason the known machines are questionable in regard to sanitation, since the required outlay for cleaning, even if it can be performed at all, is not always applied for lack of time. The employment of suitable chemicals for cleaning is not desirable for sanitary and ecological reasons. The reception of the finished ice cream following the delivery from the removal opening is also not satisfactorily solved in connection with the known machines.
Most commercially available customary ice cream machines only have a vat receptacle, on which the vat is placed loosely (the bottoms of ice cream vats are always curved), and in most cases too low, on an unsanitary rubber support; one hand is always needed to fix the vat in a position suitable for introducing the finished ice cream, and to maintain it there. These work processes are arduous and endanger the health of the operators.
No manufacturer offers a practical solution at this time in regard to the coarse additives, which are added to certain types of ice cream during their removal.
It is the object of the invention to further develop the device in accordance with the invention in such a way that an improvement of the quality of the ice cream can be achieved. In accordance with the invention, this object is attained by means of the characteristics of claim 1.
The basic concept of the invention consists in the combined effect of the inclination of the processing container and of the tools, which operate exclusively in a rotating manner and therefore can be employed for processing the liquid mixture into ice cream, as well as for ejecting the finished ice cream.
Advantageous embodiments of the attainment of the object in accordance with the invention can be taken from the dependent claims.